1. Field of the Invention
The present invention relates generally to a method for bleeding a hydraulic brake system of a vehicle; and, more specifically, to a method wherein the brake system includes a brake circuit whose pressure can be selectively increased by a pump.
2. Description of Related Art
Modern vehicles having hydraulic brake systems typically require a process known as bleeding. Bleeding as applied to hydraulic brake systems is a process used to purge or evacuate air or gas bubbles from the brake system. Activation or depression of the brake pedal may cause compression of air or gas bubbles remaining in the system leading to elastic behavior of the brake transmission path and increased pedal operation travel. Increased pedal travel is perceived by the driver as disturbing and in extreme cases can also represent a safety risk.
For various reasons, it is not always possible to obtain perfect air-free filling of the brake system during the initial filling procedure of a brake system with hydraulic fluid occurring in vehicle production. As set forth above, even if safety-critical thresholds are not exceeded unaccustomed long pedal operation travel leads to driver discomfort and correspondingly may result in returns or service visits, which should normally be avoided for a new vehicle.
A conventional bleeding process includes introducing hydraulic fluid from a pressure source at a point in the brake system; opening one or more bleed valves at other points; and allowing continuous hydraulic fluid flow through the bleed valves until no bubbles emanate from the bleed valve, requires a relatively high cost, so that such bleeding seems impractical as an obligatory step during vehicle production for time and cost reasons. Such systems may also require additional equipment and increased time costs, both during production of the vehicle and following repair work on the brake system.